Process for preparation of complex formal synthetic lubricants by a formal interchange



. o eration.

United. States Patenti PROCESS FOR PREPARATION OF COMPLEX 1' FORMAL SYNTHETIC LUBRICANTS BY A FORMAL INTERCHANGE Alfreffi. Matuszak,'Wcstfield, and Harold R. Ready, 'Roselle Park, N. 3., assignors to Esso Research and Engineering Company, a corporation of Delaware N Drawing. Application March 31, 1955 t 1; Serial No. 498,458

p Claims. 01. 260-615) This invention relates to synthetic lubricating oil compositions. Particularly, the invention relates to synthetic.

lubricating compositions of the complex formal type and to an improved process for their preparation. Still more particularly, the invention relates to a process for preparing'complex' formals in the synthetic lubricating oil range byaQn'-step process of formal interchange. The

rials wi'th lubricating properties.-- In general, these new I 1 synthetic lubricants arecharacterized' by viscosity properties that are outstanding at both low and high temperatures, especially when compared tomineral. oils. Th" se outstanding low and high temperature properties:

at specially desirable for use in equipment designedto op rateover a greattemperature differential, such as jet engines for aircraft use, combustion engines for aircr'af and the like. It has been found that mineral lubhcating oils are generally, undesirable for thelubricatingof theseeng'ines because of their'high and low temperature viscosity limitations. 1 It has alsobeen found that synthetic lubricants may be idesirable for the lubrication of standard automotive engines." in addition to he versatility of theiryiscosities, the use 0 H p gated have. been found to result invery low rates of coinbu's'tion chamber deposit formation, particularly when used 'foi'long periods of time," Low rates of formation ofc'oinbiistion chamber deposits result in. a corresponding increase-in='lubricant life, increased power factor from "fuel, *-ai1d"a' general overall improvement in engine metyp es ofthe synthetic lubricants investi- Forus'e in reciprocating engin'es, particularly'as' alubricant .for automotive engines, a lubricating composition mltst' meet "several requirements. efiective lubricating film and to maintain that filmat low detailed examplesjare given:

inspection tests for synthetic lubes and the data Inorder to form an andh'i'gh temperatures it must have certain viscosity characteristics. Atlow' temperatures the lubricant must'be sufiiciently labile to flow through the circulatory system of the equipment and allow movement of lubricated sur faces without an undue power requirement. A lubricant having an ASTM pourfpoint below about +20 F...has suflicient low temperature lability to make it satisfactory in these respects for general use. At high temperatures a lubricant must have sufficient body or thickness 'to furnish and maintain a satisfactory lubricating film. It has been found that a lubricant that is satisfactory in this respect will have a viscosity at 210 F. of between about 30 and 110 Saybolt seconds, Universal. To prevent undue lubricant loss, due to volatility and general molecular disintegration and. to insure against explosion hazards at higher temperatures sometimes encountered, a lubricating composition should have a.-fiash point in excess of about 350 F. These requisites are inherent in the term lubricating compositions, as used inthis specification, and the formals prepared by the process of this invention are limited to those within these operable ranges. The preferred materials, as contemplated herein and as described'in the preferred embodiment hereof, will have an ASTM pour point below about -15 F., a flash point above about 375 F., and will have a viscosity Within the range of 35 to Saybolt seconds, Universal at 210 F. It has been found that formals .having between about 20 to-l30 carbon atoms are useful as syntheticlubricants and particularly between about 25 and l00-carbon atoms. The materials prepared in accordance with the inventive concept are within thisrange.

As was stated above, the instant improved process for the preparation of complex formal synthetic lubricants involves a simple formal interchange procedure in the presence of a' suitable catalyst. In this improved process a glycol or glycol reactant is admixed with a simple have hitherto been found necessary in the preparation of materials of this type. and the preferred conditions of temperature and pressure are set out more in detail below. In order to more exprocess, the 7 following The catalysts that are operable plicitly illustrate theinventive EXAMPLE 1 On'emolecular proportionj'of isooctyl formal was ,adf' mixed withone molecular proportion of triethylene glycol;

Toluene sulfonic acid in -a oneliter distillation flask; (0.5 wt. percent) was added as the catalyst. The mixture was heated at 25 mm./Hg until about one mol of isooctyl This amount of alcohol was evolved in about minutes T of heating time.

The product obtained was submitted to the standard is set out in Table I below.

EXAMPLE II head, having -a boiling point of 90l00 C. at this pressure, The product was washed with caustic and again with Water. v

The material was then stripped to a temperature of 210 C. at 8 mm/Hg pressure and the resulting'product. submitted to the standard inspection tests. Data obtained are set out in' Table I below.

" EXAMPLE III A mixture of two mols of isooctyl formal and one mol of triethylene glycol was heated at 30 nun/Hg pressure for 3 hours. No catalyst was used in this preparation.

-At the end of the three-hour heating period, the product Table I below.

EXAMPLE iv 1 it Two mols of triisodecyl formal, one mole of tetraethylene glycol, and 0.4 wtipercent of toluene sulfonic acid was heated for three hours at 8 mm./Hg pressure. 1.7

Patented June 10, 1958 This simplified one-step 'prohad the properties set out in mols of triisodecyl alcohol was distilled overhead at 122-l29 C.

The product was washed with caustic and then with water. 'After washing, the material was stripped to a liquid temperature of 210 C. at 8 mm./Hg pressure. The final product had the properties'set out in Table I below.

EXAMPLE V One mol of isodecyl formal, one mol of tetraethylene glycol, and 0.5 wt. percent of sodium acid sulfate were heated for one hour at 30 mm./Hg pressure. 0.5 mol of isodecyl alcohol was removed overhead (B. P. 116- 135 C./30 mm./Hg). The product was washed with caustic and with water and stripped to a liquid temperature of 185 C. at 6 mm./Hg pressure. The resulting material had the properties set out in Table I below.

EXAMPLE 7 VI Two mols of isodecyl formal, one mol of tetraethylene glycol and 0.5 wt. percent of toluene sulfonic acid were heated for one hour at 25 mm./Hg pressure. One mol of isodecyl alcohol was removed (B. P. 110-112 C./25 mm./Hg). This material was caustic washed and then water washed. After stripping to a liquid temperature of 220 C. at mm./Hg pressure, the product had the properties set out in Table I below.

EXAMPLE VII A glycol. of the type formula triethylene glycol (formal-'triethylene glycol) that is,

HO (C H4O) [CH O--(C H O -H was prepared as follows: i i

2253 grams 1s mols) of triethylene glycol, 330 grams of paraforinaldehyde, equivalent to 11 mols of formaldehyde excess), 200 grams'hexane, and 11.2 grams sodium acid sulfate catalyst; were heated (refiuxedyto a maximum temperature of 108 C. over a period of 7 "hours to give 2453 grams (5 mols) of the triethylene obtained overhead, leaving as a product 80 grams "of-a material having the properties set out in Table I below.

Portion B was diluted with 200 grams of hexane and washed with saturated sodium carbonate solution. This washing Was followed by a Water wash and by a sodium chloride solution wash. After the washing steps, the product was filtered and stripped to a liquid temperature of 200 C. at 0.1 mrn./Hg pressu'reJ 119 grams of a' material was obtained which had the properties set out in Table I below.

Table l.--Complex formal synthe An examination of the data of Examples I-VII shows that the process of this invention may be used to prepare complexformal synthetic lubricants which have excellent properties, making them especially suitable for use as lubricating oil bases or components.

The glycol reactant which is operable in the improved process of this invention may be selected from a large number of materials. Exemplary are glycols of the formula HOROH wherein R is an alkyl group containing from about 2 to about 30 carbon atoms. The glycol reactant may be of branched or straight chain configuration. For instance, polyalkylene glycols, the butane diols, the pentane diols, are operable as are the substituted diols such as 2-alkoxymethyl-2,4-dimethyl pentanediol-l,5. In the preferred embodiment of this invention, polyalkylene glycols are contemplated which have the formula HO(C,,H ,,O),,H wherein n and y are numbers of from 1 to 6. Particularly preferred are the polyalkylene glycols of the formula wherein n is 2 and wherein y is a number of from 2 to 6.

h The formal component of the improved proeess is prepared by reacting two mols of the desired alcohol with formaldehyde ora formaldehyde donor in the presence of' a suitable catalyst. Other operable conditions are temperatures in the order of 50 to 225 C(and pressures ranging from about 250 to about 1 mmJHg.

The formals may also be prepared by reacting a molar proportion of the desired alcohol with formaldehyde or wherein R and R" are alkyl groups of the reacting alcohol and contain from about 4 to about 26 carbon atoms.

Particularly preferred are the formals of the highly i branched chain primary alcohols obtained by carbonyla tion and hydrogenation of olefins in-the Oxoprocess. These alcohols are well known to the art and are generally referred to as OX0 alcohols.

As was stated above, the final complex formal contain from about 20 to about 130 carbon atoms, preferably 25 to 100 carbon atoms, and the initial reactants will be chosen so as to obtain a product having the desired structure and carbon chain composition. 'Although in the examples given as illustrative, toluene sulfonic acid and sodium acid sulfate were used as catalysts, it is to be understood that any of the cornrnonly known esterification catalysts may be employed, in the process of this invention, for instance, such cata-.,- lysts as sodium acid sulfate, p-toluene sulfonic acid, Ordinarily,

sulfosalicyclic acid, phosphoric acid, etc.

from about 0.2 wt. percentto about 1.0 wt. percent of the catalyst is suficient, with from 0.3 to 0.5 wt. per-; cent' being preferred. The percentage of catalyst used;

is based on the weight of the total composition.

The proportions of the complex formal and the formal which are used in the improved process will depend tic lubricants Example VII Ex. 1 Ex. II Ex. III Ex. IV Ex. V Ex. VI

. Portion Portion Viscosity (BUS):

210 F 126 37. 8 52. 4 i1. 3 40. 7 48. 2 254 44, 0 100 F. 785 67. 8 167. 7 107. 7 103. 0 146. 4 1850 121. 0 F 53, 000 965 4, 850 3, 900 3, 350 4, 850 4, 010 "iseosity Inde 139 172 161 140 108 16 132 156 P0111 Point, 35 35 (-35 65 -25 70 Flash Point, F 425 370 370 395 370 405 425 375 Acid No. (mg.KOH/g.) 1. 9 0.6 0.7 0. 3 0.2 0. 3 0. 40 0. 4 Hydroxyl No. (mg.KOH/g.) 47 8. 0 6. 6 23 17 47 somewhat upon the desired final product. Satisfactory synthetic lubricating oils may be obtained by utilization of from 2 to 12 mols of a formal with from about 1 to 6 mols of a glycol reactant.

The temperatures and pressures utilized in the process of this invention may vary between about 50 and 250 C. and from about 0.1 to about 760 mm./Hg. Preferred operating conditions are from 90 to 190 C. and from 5 to 30 mm./Hg. The time of the reaction will be dependent upon the product desired but ordinarily the theoretical quantity of displaced alcohol will be distilled overhead in from about 1 to about 3 hours.

As was stated above and as is shown by the examples, the time-consuming and expensive washing procedures may be eliminated by the process of this invention. However, outstanding synthetic lubricants are obtained by finishing the product with a caustic wash usually followed by a water wash and/or a wash with a salt solution.

The desired viscosity is obtained by stripping the reaction product to remove materials of lower viscosity and lower boiling points. Although the stripping conditions will depend on the final product desired, liquid temperatures of from about 150 to about 200 C. at 0.5 to 10 mm./Hg pressure have been found to result in synthetic lubricants of the desired properties.

The synthetic lubricants prepared by the inventive process are compatible with various additive materials with which the art is familiar. Particularly, viscosity index improvers, pour point depressants, sludge dispersants, oxidation inhibitors and the like may be blended with these formals to enhance special properties thereof.

To summarize briefly, the instant invention relates to an improved process for the preparation of complex formal type synthetic lubricants. Improved process comprises the steps of mixing from about 1 to 6 mols of a glycol reactant with from about 2 to 12 mols of a formal in the presence of from 0.2 to 1.0 wt. percent of a catalyst and subjecting the mixture to a temperature of from about 50 to 200 C. and at a pressure of from about 250 to 1 mm./Hg. The reaction is carried out until theoretical alcohol is removed overhead and the product is stripped to a liquid temperature of about 200 C. at a pressure of about 0.5 to 10 mm./Hg. If desired, the product, prior to the stripping step, may be caustic washed followed by other washing steps, although this procedure is not necessary. The preferred glycols have the formula HO(C,,H ,,O) H wherein n and y are numbers of from 1 to 6, preferably 2 to 6. The preferred formal has the formula R--O-CH -O-R wherein R and R are alkyl groups having from 4 to 26 carbon atoms, preferably from 6 to 18 carbon atoms. The highly branched chain alkyl groups of the wellknown Oxo alcohols are particularly desirable.

What is claimed is:

1. In a process for the preparation of complex formal lubricating compositions having an ASTM pour point below about +20 F, a viscosity at 210 F. of between 30 and S. U. S. and a flash point above about 350 F, by reacting a formal of the formula wherein R and R are alkyl groups containing from about 4- to 26 carbon atoms with a glycol at a temperature within the range of about 50 to 250 C. for about 2 to 20 hours, and recovering a complex formal having from about 20 to carbon atoms per molecule, the improvement which comprises reacting said formal with said glycol in the molar ratio of about 2 to 4 moles of formal to 1 mole of glycol.

2. In a process for the preparation of complex formals containing 20 to 130 carbon atoms, having ASTM pour points below about +20 F., flash points above about 350 F., and viscosities at 210 F. within the range of from about 30 to about 110 S. U. S., by reacting a formal of the formula R-O-CH --O-R wherein R and R are alkyl groups containing about 6 to 18 carbon atoms, with a glycol having the formula HO(C H O),,H wherein y is a number of 2 to 6, at a temperature of about 90 to C. under pressures of about 0.1 to 760.0 min/Hg, for about 2 to 20 hours in the presence of an acid catalyst and stripping the reaction product to recover said complex formals, the improvement which comprises reacting said formal with said glycol in the molar ratio of 2 to 4 moles of formal per mole of glycol.

3. A process according to claim 2 wherein R and R contain 8 carbon atoms and wherein y is 4.

4. A process according to claim 1 wherein said glycol is prepared by reacting 15 mols of triethylene glycol with paraformaldehyde in an amount equivalent to 11 mols of formaldehyde.

5. A process according to claim 2 wherein R and R are the alkyl radicals of highly branched chain alcohols having from 6 to 18 carbon atoms obtained by carbonylation and hydrogenation of olefins in the Oxo process.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Hill et al.: Jour. Amer. Chem. Soc., vol. 57 (1935), pp. 925-928. 

1. IN A PROCESS FOR THE PREPARATION OF COMPLEX FORMAL LUBRICATING COMPOSITIONS HAVING AN ASTM POUR POINT BELOW ABOUT +20*F., A VISCOSITY AT 210F. OF BETWEEN 30 AND 110 S. U. S. AND A FLASH POINT ABOVE ABOUT 350*F., BY REACTING A FORMAL OF THE FORMULA 